I don't know if this will be a comfort to you, but you are not the only member of this community that has mentioned weird sensations occuring in the abdominal region and the 'southern hemisphere', !
I have no idea why this occurs, but you are not alone in this. I thought you might appreciate this article on a condition called Restless Genital Syndrome (yes, it's a real thing) -- https://multiplesclerosis.net/living-with-ms/have-you-heard-of-restless-genital-syndrome. You may not be experiencing symptoms that severe, but I thought you might like knowing what you are experiencing is normal. Well, normal when it comes to MS, that is!
Thanks for sharing!
Best, Erin, Team Member.